1. Field of the Invention
This invention relates to a hinge device to be used for a foldable apparatus comprising an apparatus main body and a cover apparatus such as a lap-top type computer, a portable telephone set or a word processor so as to make the cover rotatably fitted to the main body, said hinge device being adapted to hold the cover to any intermediary angular position relative to the main body between the fully closed position and the fully opened position and release the cover from the intermediary angular position when appropriate force is applied to the cover so that the cover may be opened and closed smoothly.
2. Prior Art
Known lock means including claw clutches and magnets that are adapted to prevent the cover of an apparatus such as a portable telephone set from being inadvertently closed in use or opened when not in use are not satisfactory particularly in terms of limited applicability, high cost and inconvenience of operation. In an attempt for dissolving the drawbacks of the prior art, Japanese Patent Application Laid-Open No. 7-11831 proposes a hinge device as briefly described below.
A hinge device according to the above patent document has a configuration as schematically illustrated in FIGS. 7 through 10 of the accompanying drawings. Referring firstly to FIGS. 7 and 8, an apparatus main body 1 and a corresponding cover 2 are put together by means of the hinge device in such a way that they may be opened relative to each other by an angle of .alpha..degree. and closed from that angular position. The hinge device 3 is constituted by a pair of main body hinge sleeves 1a integrally formed with and secured to the main body 1 and a pair of cover hinge sleeves 2a also integrally formed with and secured to the cover 2 and the abutment facet 1b of each of the main body hinge sleeves 1a and the corresponding abutment facet 2b of the mated one of the cover hinge sleeves 2a slide on each other when the cover is turned open and closed as seen from FIG. 8.
A fixed disk 4 is fitted into each of the main body hinge sleeves 1a in such a way that it cannot rotate but can axially move relative to the hinge sleeve 1a by way of mutual engagement of a guide rib 1c formed on the inner peripheral surface of the main body hinge sleeve 1a and a corresponding guide groove 4a formed on the outer peripheral surface of the fixed disk 4. On the other hand, a movable disk 5 is fitted into each of the cover hinge sleeves 2a in such a way that it cannot rotate relative to the hinge sleeve 2a. In the case of the illustrated arrangement, rib 5a formed on an end facet of the movable disk 5 is held in engagement with groove 2c formed in the inside of the cover hinge sleeve 2a.
Additionally, in the above known hinge device, either the fixed abutment facet 4b of the fixed disk 4 or the movable abutment facet 5b of the movable disk 5 (the fixed abutment facet 4b in the illustrated instance) is provided with a plurality of (three) engaging recesses 6 arranged peripherally at predetermined angular positions N1, N2 and N3 (as defined by the opening angle .alpha..degree. of the cover 2) as seen from FIGS. 9A, 9C and 10, while the other of them is provided with the a plurality of (two) corresponding engaging projections 8 arranged peripherally at predetermined angular positions P1 and P2 and projecting from the movable abutment facet 5b as seen from FIGS. 9B, 9D and 10, the engaging recesses 6 and the corresponding engaging projections 8 being adapted to be urged into mutual engagement by a coil spring 7.
As seen from FIG. 10, the coil spring 7 is housed in a storage cavity 4c having an opening at the side of the fixed disk 4 opposite to the fixed abutment facet 4b. Then, a rod 9 is driven from the outside of the remain body hinge sleeve 1a to run through the coil spring, the fixed disk 4 and the movable disk 5 so that the front end 9a of the rod is tightly received in threaded hole 2e cut into the bottom 2d of the cover hinge sleeve 2a In FIG. 10, reference symbol 9b denotes the head of the rod 9.
As a result of this arrangement, the coil spring 7 resiliently presses the fixed disk 4 against the movable disk 5 and urges the engaging recesses 6 and the corresponding engaging projections 8 into mutual engagement. In other words, the fixed abutment facet 4b is pressed against the movable abutment facet 5b.
Thus, it will be appreciated from FIG. 10 that, as the cover is moved to become open, the movable disk is rotated with the cover hinge sleeve 2a, the engaging projections 8 projecting from the movable abutment facet 5b of the movable disk 5 are moved peripherally and released from the mutual engagement with the corresponding engaging recesses 6 as shown in FIG. 9E. Then, the fixed disk 4 is moved leftward in FIG. 10 against the resilient force of the coil spring 7 so that the front ends of the engaging projections 8 are made to slide peripherally on the fixed abutment facet 4b.
Therefore, referring to FIGS. 9A through 9E, while the engaging projections 8 of the movable disk 5 arranged at angular positions P1, P2 are held in engagement with the corresponding engaging recesses 6 of the fixed disk at angular positions N1, N2 so long as the cover 2 is closed, they come to be engaged respectively with the engaging recesses 6 located at angular positions N3, N1 when the cover is opened by angle .alpha..degree. .
The above described known hinge device represents a major technological advancement over known lock means including claw clutches and magnets because the cover is effectively prevented from being inadvertently closed in use or opened when not in use and can be operated to become open and closed in a very simple way.
While the above described known hinge device is highly effective, it requires a cumbersome assembling process. More specifically, as may be seen from FIGS. 8, 9A through 9E and 10, firstly the cover hinge sleeve 2a is fitted to the cover and the groove 2c is made to become engaged with the rib 5a, while the fixed disk 4 is fitted into the main body hinge sleeve 1a so that the guide rib 1c is made to become engaged with the guide groove 4a of the fixed disk 4. Then, the coil spring 7 is put into the fixed disk 4 and the rod 9 is driven to move through the coil spring 7 until the threaded front end 9a of the rod 9 is tightly held into engagement with the corresponding threaded hole 2e bored through the bottom 2d of the cover hinge sleeve 2a so that the coil spring 7 is compressed by the head 9b of the rod 9 to by turn press the fixed abutment facet 4b of the fixed disk 4 against the movable abutment facet 5b of the movable disk 5.
The present invention is intended to eliminate the above cumbersome assembling operation. In an aspect of the present invention, there is provided an engagement assembly with which a rod is made to pass through a second (movable) disk, a sliding disk and a coil spring and become securely and unremovably received by a first (fixed) disk so that the sliding disk is made to resiliently abut the second (movable) disk under the effect of the coil spring, while a pair of spaces are provided between the sliding disk and the remote ends of the sliding grooves of the first (fixed) disk. With this arrangement, the sliding disk is made free from any obstruction when it is axially moved as the second member (cover) is opened or closed relative to the first member (apparatus main body).
The engagement assembly becomes engaged with the first (fixed) disk and the second (movable) disk simply by aligning the first (fixed) disk of the first member (apparatus main body) and the second (movable) disk of the second member (cover) and bringing them into mutual engagement. Then, the second disk is unreleasably held to the second hinge sleeve so that the first member and the second member are made to pivot on each other so as to become closed or open. Thus, the first object of the present invention is to provide a hinge device to be suitably used for a foldable apparatus that can be assembled with utmost ease.
Preferably, the rod running through the second disk, the sliding disk and the coil spring and secured to the first disk is riveted at the front end thereof so as to make the washer abut the front abutment edge of the shank section of the rod and the first disk and hence make the rod itself unreleasable. This arrangement can significantly improve the integrity of the engagement assembly.
Preferably, the second disk is made to have a base plate section and a resilient claw section, of which the resilient claw section includes resilient anti-release claws that become engaged with the second hinge sleeve when the engagement assembly is fitted into the first and second hinge sleeves so as to make the anti-release edge section of the second hinge sleeve to be pinched between the resilient anti-release claws of the resilient claw section and the base plate section. With this arrangement, the engagement assembly would not inadvertently come off from the first and second hinge sleeves.
Still preferably, the engagement assembly is provided at an end thereof with a closure cap that can be fitted to the engagement assembly with a simple operation in order to improve the appearance of the apparatus and prevent particles of dirt from entering the engagement assembly.